In general, existing building wall surface decoration are made by bonding wall ties to walls by means of a bonding coat (e.g. mortar). In such a technique, there exist the technical problems of low construction speed, heavy dead weight of wall surface decoration layer, potential safety problem of falling wall tiles, etc. The frequent occurrence of exterior wall tile dropping has drawn more and more attentions to the safety of wall tile decoration. In the mean time, wall decoration cannot provide a variety of options due to limited patterns and colors available for wall tiles. Another kind of building wall surface decoration uses exterior wall coating decoration applied by spray coating or brush rolling. Disadvantages of this technique are limited pattern options and difficulty in applying complicated patterns.
As building energy conservation technology becomes more and more popular, external insulation systems for exterior walls have been developed vigorously. However, the potential safety problem on a long term basis in applying wall tiles in an exterior wall's external insulation system was test-verified. Since 1985, the Fraunhofer Research Institute in Holzkichen, Germany, had conducted long-term experiments on paving ceramic wall tiles in external insulation system. The site of the experiments were test walls and houses exposed to atmospheric environment. After about 10 years, the ceramic tiles on the test walls peeled off over a large area. Following conclusions are made based on the experiments made by the Fraunhofer Institute:
(1) Potential quality problem of the applied ceramic tiles will only occur after a long period of time (about 10 years).
(2) Enhancing waterproof protection may extend their service life.
(3) A bonding coat under the ceramic tile must be a coat with a specific mechanical strength and hydrophobic performance. And, mineral-based lightweight face coat is not suitable for this application.
To overcome these problems, technicians in this field extend the service life (prevent peeling) of paved ceramic tiles by applying waterproof protection and enhancing bonding strength. For instance, Professor Zhang Yongming, Tongji University, China proposed that each aspect of pavement of ceramic tiles for an external insulation system, including material and process, should be addressed and emphasized the control of deadweight of ceramic tile preferably at 20 kg/m2 or below and the enhancement of performance of the bonding material. Disadvantages of these methods lie in that special requirements are raised for the performance of ceramic tiles and bonding material and potential long-term quality problem still exists since it's difficult to control the construction process.
FIG. 1 indicates an existing external insulation system using bonded ceramic wall tiles. The entire process includes: handling a base wall 3—pasting insulation material 8 by means of adhesive material 9—applying a base coat 2 with mesh fabrics—fixing anchor bolts 12—applying a ceramic tile bonding coat 11—paving ceramic tiles 10—filling seams 13.
There are also some other methods. For instance, in Chinese patent CN2849002Y, grooves are provided on the back of a tile so as to enhance bonding strength of wall tile. This method, however, still involves risk of peeling and it introduces an additional procedure, increasing the cost of production.
In conclusion, in this field, there is a need for a method of wall surface decoration on a buildings that provides a wall surface which is safe and solid, of a long service life, available of a variety of patterns and convenient to construct.